Investigation of a dynamic active/passive noise cancellation of polyborosiloxane thin membrane gel

Abstract

This study proposes a multifunctional, thin membrane gel based on a formulation of PDMS and boron. The proposed gel offers a dynamic passive stimuli-responsive sound absorption at low frequencies, which can be transformed to active noise cancellation with the use of a secondary sound source. The passive behaviour of the proposed material is the result of a dynamic phase transition in the material’s polymeric network, activated by the interaction with the travelling sound pressure wave. The presence and extent of the phase transition in the material was investigated via Fourier transform infrared spectroscopy and oscillatory rheological measurements, where it was found that the amount of boron in the gel has a crucial role on the occurrence of the phase transition and consequently on its acoustic performance. The passive scenario results revealed a high and dynamic absorption of approximately 80% at the absorption coefficient peaks, which dynamically shifted to lower frequencies while sound amplitudes were increased. The active noise cancellation was successfully demonstrated at the lower frequencies range, as the occurrence of the phase transition was actively controlled via the sound pressure wave introduced. The aforementioned phase transition was intensified, with energy consumed in this process, resulting in a dynamic noise cancellation. These results demonstrated that the proposed gel membrane material can be used to develop active/passive deep subwavelength absorbers with unique properties, which can dynamically tune their performance in response to external stimuli, and that can be further controlled/activated with the use of mechanical transducers.

Tunable and broadband low-frequency noise control via multifunctional polyborosiloxane thin membrane gels

“…In previous work 19 , we introduced these SSG based thin-membranes and managed to achieve high absorption coefficients (α > 0.9),in the low frequency range, which dynamically shifted to lower frequencies as the sound wave pressure wave was increased. In our following work we also demonstrated that this behaviour can be actively controlled, by the introduction of a secondary sound source, for applications where active noise control is required 20 . In this work, we demonstrate that the combination of thin membrane gels containing different amounts of B-O bonds can result in new high absorption peaks, not only due to the underlying mechanism of SSGs, but also due to the interaction between the membranes themselves, thus providing a highly tailorable solution for applications where noise cancellation at multiple frequencies is required.…”